//C07:exec_7_13.c -- strcat();
#include <stdio.h>

void my_strcat(char arrA[], char arrB[])
{
    int cnt = 0;
    int i = 0,j = 0;
    char arrC[30];
    while(arrA[i] != '\0')
    {
        arrC[cnt] = arrA[i];
        cnt++;
        i++;
    }
    while(arrA[j] != '\0')
    {
        arrC[cnt] = arrB[j];
        cnt++;
        j++;
    }
    
    arrC[cnt + 1] = '\0';
    printf("%s\n", arrC);
}

int main(void)
{
    char arrA[] = {"ABC"};
    char arrB[] = {"DEF"};
    my_strcat(arrA, arrB);
}